I'm a noob just started playing the last week but the buddy i'm playing with thinks Vader has the ability to fire his primary and secondary weapon during the combat phase I say no because rule states one or the other am I missing something?

You can only fire one (primary OR secondary) weapon in one Combat Phase. There really isn't any disputing it as it's all over in the rulebook (Top of Page 10, bottom of page 10- this time with a bold red "NOTE" in front of it, under Roll Attack Dice on page 11 - specifically calling out primary vs secondary). Only one attack per round per ship. An Action is not an attack if that is what your opponent keeps getting caught up on.

+1…

Vader has 2 actions, so after he moves he can select 2 different action of the 4 available to him (Focus, Target Lock, Barrel Role, Evade). If Vader has an upgrade card that has "Action:" in the wording, he can also select as one of his 2 actions.

Movement and action selection(s) are completed for ALL ships before combat phase starts… So no you cannot fire both primary and secondary weapons in the same combat round, with ANY ship.

The only exception even close is the Falcon/Slave with a gunner, which allows an addtional attack if the first one does not result in a "hit".